The present invention relates to a fixed material transportation apparatus, an fixed material discharging apparatus, a method for discharging the fixed material, and a liquid fixing apparatus having the carrier apparatus and the discharging the apparatus, particularly to technology for drawing, keeping, and discharging smoothly the fixed material in a recording portion of the liquid fixing apparatus after finishing to fix.
FIG. 15 is a side view showing an example of inner construction of an ink jet printer being one of general liquid fixing apparatus and discharging recording a medium. The ink jet printer includes a sheet feed roller 1 and a hopper 2 as an automatic sheet feeder, includes a delivery roller 3, a driven roller 4, a transportation stage 5, a discharging roller 6, and a roller with teeth (a discharging serrated roller) 7 as a carrier, and includes a carriage 8 and a recording head 9 as a recorder.
The ink jet printer having such the construction feeds a sheet, for example, which is recording medium by the automatic sheet feeder, and prints letter and picture by discharging ink droplet on the sheet using recording device while transporting the sheet by transportation apparatus. That is, a control portion of the ink jet printer presses recording media P of plural sheets piled in the hopper 2 to the sheet feed roller 1 by raising the hopper 2 rotating the sheet feeder 1 and feeds the top sheet of the recording media P separating from the lower part of the recording media P. The recording media P is sandwiched between the delivery roller 3 and the driven roller 4 and transported onto the transportation stage 5 rotating the delivery roller 3.
Next, ink of each color is supplied to a pressure generating chamber of the recording head 9 mounted at the carriage 8 from ink cartridges of total four colors of yellow, magenta, cyan, and black for example, and ink droplets are discharged to the recording medium P from a nozzle opening pressurizing ink in the pressure generating chamber. At this time, highly accurate ink dot control, halftone process, and the like are performed by controlling discharging timing of each color ink and driving of the carriage 8 and the delivery roller 3. The recording medium P is discharged onto a discharging stacker not shown rotating the discharging roller 6 by sandwiching the recording medium between the discharging roller 6 and the discharging serrated roller 7.
In such the ink jet printer, pressing force of the discharging serrated roller is set to degree that a spur mark (a scar of rowel spur) does not remain on the recording medium P at discharging the recording medium P as shown in FIG. 16A. However, in the case that picture where many ink particles are discharged on the recording medium P like solid picture is recorded, the recording medium P absorbs a lot of ink and expands in wave shape to the recording head 9 side so as to generate possibly so called cockling as shown in FIG. 16B.
There are faults that recording unevenness generates by dispersion of flying distance of ink particles because gap between the recording medium P and the recording head 9 becomes narrow and the recording medium P gets dirty because of attaching to the recording head 9 at generating the generation of the cockling. Even in the transportation apparatus of the recording medium shown in FIG. 16A, it is possible to prevent the above faults by depressing the above cockling within tolerance if the span between the delivery roller 3 and discharging roller 6 is comparatively short.
However, it is necessary in near future to increase number of nozzles of every nozzle of each color or to arrange nozzle lines of plural colors to transportation direction of the recording medium to make recording speed further high in the ink jet printer and the like. In these cases, dimension of the recording head becomes long to transportation direction of the recorder medium as shown in FIG. 16C. When the recording head 9 is long, span between the delivery roller 3 and the discharging roller 6 becomes long so as not to prevent the cockling absolutely and so that the cockling gets over tolerance in the construction transporting and discharging by sandwiching the delivery roller 3 (and the driven roller 4) and the discharging roller 6 (and discharging serrated roller 7 as the driven roller thereof). Therefore, the cockling goes over allowance, and it is considerable that the construction transporting and discharging by sandwiching with such the two pairs of rollers itself is not realized depending on kinds of apparatus such as the ink jet printer having long head length and the like.
Such the cockling is comparably small at using exclusive sheet for ink jet printer and the like as a recording medium, and is large at using normal sheet. Because of that, paper gap [gap A between the recording medium P and the recording head 9 in FIG. 16A] is set large considering rise of the sheet caused by cockling at using the normal sheet in the design of ink jet printer and the like. However, when the paper gap is large like this, ink particles discharged from the nozzle of the recording head generate flying curve and divergence of point of impact becomes large for the flying curve so as to prevent possibly from improving printing quality even at using needless exclusive sheet.
Further, when the recording medium P rises by cockling, the floated recording medium P is pressed by the discharging serrated roller 7 as shown with arrow B in FIG. 16B, thereby the spur mark run over caused by the discharging serrated roller 7 remains at the recording medium P as shown in FIG. 17. The spur mark is conspicuous especially at the normal sheet large in cockling and causes decreasing printing quality.
On the other hand, various kinds of printers having mainly a sucking portion of hollow box shape at transportation surface of the recording medium and sucking the recording medium through plural sucking holes (through holes) provided at the sucking portion by a sucking pump and the like are proposed in recent yeas (see JP-A-63-303781, JP-A-3-270, etc.). Among them, there is a printer proposed that the recording medium is sucked or stuck to a platen and the like through these sucking holes.
However, only through holes are opened to suck at the sucking portion of the hollow box shape in both of them, and it is difficult to prevent the above cockling over whole surface of the recording medium in the recording portion. A projecting part from the recording portion of the recording medium rises and is pressed by the discharging serrated roller 7 as shown with arrow B in FIG. 16B. As the result, it can not prevent that the spur mark remains at the recording medium P.
Further, since the prior art described in the above official gazette has the construction that only through holes are opened to suck at the sucking portion of the hollow box shape, strong sucking force possibly causes fall of transporting accuracy. Because of that, in the present circumstances, a printer is not made practicable except a part of large-sized printer performing transportation (using its own weight of the sheet for transportation) to gravity direction as the actual situation.
The above ink jet printer can print a forward end (upper end, hereafter) of transportation direction and a backward end (lower end, hereafter) of transportation direction of the recording medium P without a margin. The printing without margin of upper and lower ends is need that transportation speed of the recording medium P by the delivery roller 3 is changed to slower speed than normal speed and a part of nozzles is used for ink discharging to the recording medium P by the recording head 9.
Thus, although the printing without margin of upper and lower ends can not use whole nozzles, the reason is as the following. That is, although ink run off from the upper and lower ends of the recording medium P is stuck on the transportation stage 5 at performing the printing without margin of upper and lower ends, the recording medium P is possibly contaminated when ink is stuck on the transportation stage 5. Then, ink absorbing materials 5b and 5c receiving and absorbing ink run off from the upper and lower ends of the recording medium P are buried at both sides of a rib 5a formed at the transportation stage 5 to keep paper gap between the recording medium P and the recording head 9 and to reduce transportation resistance generating between the recording medium P and the transportation stage 5 as shown in FIG. 15.
Gap of the ink absorbing materials 5b and 5c varies by number of nozzles using for the printing without margin of upper and lower ends. For example, when the numbers of nozzles using for the printing without margin of upper and lower ends are increased, gap of the ink absorbing materials 5b and 5c must be close, thereby the length of the rib 5a becomes necessarily short. However, the rib 5a needs some degree of length to support the recording medium P firmly and to keep stable paper gap.
Therefore, number of nozzles enabling to use is determined necessarily considering necessary length of the rib 5a and accuracy of start of the recording medium P, accuracy of length of the recording medium P, each dispersion of transporting accuracy, not printing at the rib 5a at the printing without margin of upper and lower ends even in the case of the shortest start, and not printing at the rib 5a at the printing without margin of upper and lower ends even in the case of the shortest length of the sheet.
That is, the printing without margin of upper and lower ends can not perform using whole nozzles, ink must be discharged by a part of nozzles, therefore it is necessary to transport the recording medium P with slower speed than usual speed. Therefore, printing work time becomes long because printing speed without margin of upper and lower ends becomes slower than normal printing speed. Disturbance of picture quality possibly generates at border part of process domain without margin of upper and lower ends and normal process domain because transportation quantity of the recording medium P without margin of upper and lower ends becomes less than transportation quantity of normal recording medium P.